Method of shutting off water sands in wells



July 20, 1937. T. w. PEW

METHOD OF SHUTTING OFF WATER SANDS IN WELLS Filed April 24, 1935OllSand.

wATli f ThomasMPe Patented July 20, 1937 UNITED. STATES PATENT OFFICEMETHOD or SHUTTING OFF WATER SANDS m WELLS My invention relates tomethods oi closing off the entrance of water to an oil or gas well fromwater sands adjacent the oil and gas sands.

In the drilling of wells for oil and'gas it is the usual custom to drillthe well down to producing sand and set a casing above the sand and thendrill thru into the oil or gas sand. In doing this it rather frequentlyhappens that the bit penetrates water sands adjacent to the oil and gassands so that water coming into the .well from the said water sandsmixes with the oil from the oil and gas sand and interferes with theflow of the oil from the well, and in many cases practically kills thewell so that it will no longer Where the well is drilled through theproducing sand into water sand below the oil and gas sand it has beencommon to introduce cement into the well to fill the same up above thewater 20 sand so as to close oil the water. Thus a cement plug is formedin the bottom .of the well extending up somewhat above the level of thewater sand and so filling the well that no water can enter. This use ofa cement plug is only temporarily successful for the reason that waterwill gradually seep upwardly around the cement plug and finally getaccess to the oil and gas stratum and eventually flow in in suificientvolume to kill the well.

30 It is an object of my invention to provide a method of cementing offthe water sands so that they will be closed against the entrance ofwater therefrom to the well bore and the seeping of the water around thecement into the well will 35 be avoided;

I desire to introduce cement into the water stratum and force the samedeeply into the sands around the well bore and by filling up the poresand interstices in the water sand adjacent the 40 well bore to thusprevent the entrance of water to the well or to the oil and gas sandsadjacent thereto.

The method may be employed wherever water bearing strata a"e encounteredin the drilling of 5' the well.

In the drawing herewith, Fig. 1 is a central vertical section through awell equipped with the usual casing and tubing.

Fig. 2 is a similar view showing the lower end 50 of the apparatus withthe water sand cemented off.

In the drawing I have shown a situation in an oil well wherein myinvention may be carried out.

I have shown the well I as extending downwardly 55 through the overlyingearth stratum 2, and

during the operation of the well but which may 3 is shown a stratum 4,which may or may not be present, and consists of shale, gumbo, or thelike, and below this stratum is a water sand 5. The well is shown ashaving therein a casing 6 5 at the lower end of which is a casing shoe 1At the upper end of the casing is a casing head 8 having a laterallyextending pipe 9 controlled by a valve l0 through which fluid may enteror pass out of the well. The upper end of the casm ing head is shown asbeing threaded to receive a bonnet H with a stufiing box l2 at the upperend thereof to seal about the well tubing or flow line l3.

The tubing I3 is shown as being equipped with a cross M at the upperend, said cross having two of its outlets closed by bull plugs IS. Theother outlet is equipped with a' pipe IS, with a valve i1 therein, saidpipe acting as a flow line also serve as a means of pumping liquid intothe well during the carrying out of the invention.

I have found that when the water is pumped into the bottom of the wellwhere both oil and water sands are exposed, the water will penetrate andflow away from the well into the water sand much'more easily than itwill penetrate the oil It may be forced into the water sand at acomparatively low pressure which will not be entirely sufficient toforce it into the oil sand.

In carrying out my invention therefore I close off thewater sand 5 byfilling said sand with cement. I do this by first washing the water sandwith clear water and forcing the water radially away from the well boreand into the water sands until the pores and interstices of the sandstratum are opened up and cleaned of material tending to clog the same.

In carrying out this invention I first have the 40 well bore filled withmud or other fluid indicated at E8 of suflicient amount to balance therock pressure. The tubing or flow line i3 is extended downwardly t apoint adjacent the bottom or the well and into the vicinity of the watersand. I introduce water to the bottom of the well through the tubing andraise the column of mud to a point above the water sand and this may beapproximately one hundred feet of water in the bottom of the well. Theupper end of the well casing is then closed by shutting in the valve l0.Fresh water is then forced in through the tubing under pressure and saidwater will flow outwardly through the water sands as previously noted.Thisiwashing of the sand is continued for a. suificient period tothoroughly wash the sand around the well bore. The amount of besufficient to thoroughly permeate the sands surrounding the well bore.The amount'will depend upon the judgment of the'operator and amountmight be from fifty sacks. I

After the cement has been pumped into the tubing mud is pumped in.following it to displace the cement out of the tubing and into the waterstratum so as to thoroughly penetrate the same on all sides.

During the operation of the cementing, I contemplate moving the tubingl3 up and down in the well so'that the bottom of the tubing is nothigher than the top of the water sand,.so as to prevent the cement fromhardening around the lower end of the tubing and also to distribute thecement equally in all directions. When all the cement has been displacedfrom the tubing by the mud, the bottom end of the tubing is raised abovethe water sand. the pump is shut down, and the valve I0 is openedslightly to operate as a choke and allow the to Sergei-a1 hundred poundsthe pump is again started and mud is circulated inthe well for a periodof about thirty The water sand will thus be completely closed off sothat a continued production of oil and gas from the well thereafter willnot be interfered with by the water from the water stratum.

Although I have disclosed my inventionas being carried out where thewater sand is below the oil sand, it is to be possible 'to carryout theunderstood that it is invention even where there is oil sand below thewater sand. This is possible where the water is due to a leaky casing orfailure of the cement to cut off the water sands above. In each case theprocess is carried out in practically the. same manner until the watersands have been thoroughly filled with sand and prevents vicinity of thewell.

In Fig. 2- I have shown the well as it appears after the cement shown atI9 has penetrated the What is claimed is:

1. A method of closing off water sands from an oil and gas wellincluding, filling the well with mud, introducing water into the lowerend of said cement under pressure into the washed water sand and forcingsaid cement deeply into the water sand radially away from the well bore,and

holding said cement in position until it hardens.

2. A method of closing off water sands from an oil and gas wellincluding, filling the well with mud, introducing water into the lowerend of said well to raise the head of mud away from the water sandstratum, closing off the upper end of the well, forcing water underpressure into said water sand and washing the same, pumping fluid cementunder pressure into the washed water sand and forcing said cement deeplyinto the water sand radially away from the well bore, continuing thepressure upon the cement and circulating mud in the well, and thengradually relieving the pressure and cleaning the well, and holding saidcement in position until is hardens.

3. In a well having oil and water sands closely adjacent to each other,the method of cutting oil the entrance to the well of water from saidwater sands, including forcing water under pressure into the water sandsto wash the pores and interstices thereof, the pressure beinginsuflicient to force the water into said oil sand, following said waterwith fluid cementitious material to fill the said water sand deeply intothe water stratum with said cementitious material, holding said cementin said sand until it sets and then washing the well.

4. A method of cementing off water sands in wells comprising forcingwater under pressure into said sands to wash the pores and intersticesthereof, then forcing hydraulic cement under pressure deeply into saidsands to close the pores and interstices thereof, maintaining saidcement in position until it hardens, circulating fluid'in' the welluntil the hole is free of cement and then washing said we 5. The methodof closing off the entrance to a well from water producing sands lyingadjacent oil and gas sands, which consists in feeding water through a.tube under pressure sufiicient to penetrate deeply-into the water sandsbut insuf- -ficient to penetrate the oil sands whereby to wash the watersands in the vicinity surrounding the well bore, forcing hydrauliccement through a tube under pressure suflicient to penetrate the washedwater sands but insufficient to penetrate the oil sands, and maintainingpressure in the well bore to hold the cement in the water sands until ithardens.

6. In a well having water'producing sands lying adjacent to oil and gassands, the method of closing off the entrance of water to the well fromsaid water producing sands including feeding water through a flow tubehaving its lower end in the water sands deeply into the water sands towash the same in the vicinity surrounding the well bore, forcinghydraulic cement through the flow tube to deeply penetrate the watersands, maintaining fluid pressure in the well bore to hold the cement inthe water sands until it hardens, and before the cement hardens raisingthe flow tube so that its lower end is above the water sands.

'7. In a well having water sands and .oil and gas sands dischargingfluid into the bore ofthe well, the method of holding back the oil andgas and permanently closing ofi the water from entrance into the well,which includes filling the well with mud, introducing water underpressure below the mud, keeping the upper discharge end of the well openuntil the mud is raised by the water to a level above the water sands,closing the upper end of the well so that the mud constitutes a barrierfor preventing the escape of the water into the oil and gas sands,continuing the introduction of water into the water sands to wash thesame, then forcing liquid cementitious material into the pores andinterstices of said water sands to fill the same with said material, andholding the cementitious material in place until it hardens.

8. In a well having water sands and oil and gas sands, the method ofclosing off the entrance of water to the oil and gas sands includingfilling the well with mud, introducing water through a flow tube belowthe mud, keeping the upper discharge end of the well open until the mudis raised by the water to a level above the water sands, closing theupper end of the well so that the mud provides a barrier for preventingthe entrance of the water into the oil and gas sands, continuing theintroduction of water into the water sands to wash the same, thenforcing liquid cementitious material through said flow tube into thepores and interstices of said water sands to fill the same with saidmaterial, maintaining fluid pressure in the well to hold the cement inthe water sands until it hardens, before the cement hardens raising theflow tube so that its lower end is adjacent, the oil and gas sands, andthen releasing the fluid pressure and withdrawing the mud from the wellso that the oilland gas may be removed. THOMAS W. PEW..

